PHP Cheatsheet: 10 Powerful Tips for Smart Coding

PHP Cheatsheet is your quick reference to master essential syntax, commands, and coding practices in PHP. Whether you’re a beginner exploring server-side scripting or an experienced developer, this cheat sheet helps you write cleaner, faster, and more efficient PHP code.

With the rise of frameworks like Laravel, Symfony, and CMS platforms like WordPress, PHP remains one of the most widely used backend languages. This updated PHP Cheatsheet ensures you always have the right commands at your fingertips.

Basic Syntax and Variables

PHP is embedded within HTML, making it ideal for building dynamic web applications. A PHP script starts with <?php and ends with ?>. Statements end with semicolons.

Example – Printing text in PHP:

<?php
echo "Hello, World!";
?>

<?php
echo "Hello, World!";
?>

Variables in PHP are declared with the $ symbol. They are loosely typed, meaning you don’t need to specify the data type explicitly.

Example – Variable declaration:

$name = "John Doe";
$age = 25;

$name = "John Doe";
$age = 25;

Data Types in PHP

PHP supports multiple data types, including strings, integers, floats, booleans, arrays, objects, and null. This flexibility allows developers to handle dynamic data effectively.

Example – Common data types:

$is_active = true; // Boolean
$price = 19.99;    // Float
$items = [1, 2, 3]; // Array

$is_active = true; // Boolean
$price = 19.99;    // Float
$items = [1, 2, 3]; // Array

Constants and Operators

Constants are declared using define() or the const keyword. Operators in PHP include arithmetic, assignment, comparison, logical, and string operators.

Example – Constants and operators:

define("SITE_NAME", "MyWebsite");
$sum = 10 + 20;
echo SITE_NAME;

define("SITE_NAME", "MyWebsite");
$sum = 10 + 20;
echo SITE_NAME;

Control Structures and Loops

Control structures like if, else, and switch allow decision-making, while loops help repeat tasks efficiently.

Example – If-Else statement:

if ($age >= 18) {
    echo "You are an adult.";
} else {
    echo "You are a minor.";
}

if ($age >= 18) {
    echo "You are an adult.";
} else {
    echo "You are a minor.";
}

Example – For loop:

for ($i = 1; $i <= 5; $i++) {
    echo $i;
}

for ($i = 1; $i <= 5; $i++) {
    echo $i;
}

Functions in PHP

Functions make code modular and reusable. PHP supports built-in functions as well as user-defined ones. Functions can have default values and return types (PHP 7+).

Example – User-defined function:

function add($a, $b) {
    return $a + $b;
}
echo add(5, 3);

function add($a, $b) {
    return $a + $b;
}
echo add(5, 3);

Arrays in PHP

Arrays in PHP can be indexed, associative, or multidimensional. They allow developers to manage large sets of data effectively.

Example – Indexed array:

$fruits = ["Apple", "Banana", "Cherry"];
echo $fruits[1];

$fruits = ["Apple", "Banana", "Cherry"];
echo $fruits[1];

Example – Associative array:

$user = ["name" => "Alice", "age" => 30];
echo $user["name"];

$user = ["name" => "Alice", "age" => 30];
echo $user["name"];

Strings and String Functions

Strings are widely used in PHP, and the language offers powerful string manipulation functions like strlen(), str_replace(), and substr().

Example – String functions:

$message = "PHP Cheatsheet";
echo strlen($message);       // Length of string
echo str_replace("PHP", "MySQL", $message);

$message = "PHP Cheatsheet";
echo strlen($message);       // Length of string
echo str_replace("PHP", "MySQL", $message);

File Handling in PHP

PHP allows reading, writing, and appending to files using built-in functions like fopen(), fwrite(), and file_get_contents().

Example – Reading a file:

$content = file_get_contents("sample.txt");
echo $content;

$content = file_get_contents("sample.txt");
echo $content;

Example – Writing to a file:

file_put_contents("sample.txt", "Hello, PHP!");

file_put_contents("sample.txt", "Hello, PHP!");

Database Connectivity (MySQLi & PDO)

PHP provides two main ways to interact with databases: MySQLi (procedural & object-oriented) and PDO (more flexible, supports multiple databases).

Example – MySQLi Connection:

$conn = mysqli_connect("localhost", "root", "", "testdb");
$result = mysqli_query($conn, "SELECT * FROM users");

$conn = mysqli_connect("localhost", "root", "", "testdb");
$result = mysqli_query($conn, "SELECT * FROM users");

Example – PDO Connection:

try {
    $pdo = new PDO("mysql:host=localhost;dbname=testdb", "root", "");
    foreach($pdo->query("SELECT * FROM users") as $row) {
        echo $row['name'];
    }
} catch (PDOException $e) {
    echo $e->getMessage();
}

try {
    $pdo = new PDO("mysql:host=localhost;dbname=testdb", "root", "");
    foreach($pdo->query("SELECT * FROM users") as $row) {
        echo $row['name'];
    }
} catch (PDOException $e) {
    echo $e->getMessage();
}

Error Handling and Exceptions

PHP handles errors through reporting functions and exception handling using try...catch. This ensures smooth execution even when issues arise.

Example – Error reporting:

ini_set("display_errors", 1);
error_reporting(E_ALL);

ini_set("display_errors", 1);
error_reporting(E_ALL);

Example – Exception handling:

try {
    throw new Exception("An error occurred!");
} catch (Exception $e) {
    echo $e->getMessage();
}

try {
    throw new Exception("An error occurred!");
} catch (Exception $e) {
    echo $e->getMessage();
}

PHP Superglobals

PHP provides predefined global arrays like $_GET, $_POST, $_SESSION, and $_SERVER. They are widely used in form handling and web development.

Example – Using $_GET:

echo "Welcome, " . $_GET['name'];

echo "Welcome, " . $_GET['name'];

Example – Using $_POST:

if ($_SERVER["REQUEST_METHOD"] == "POST") {
    echo "Hello " . $_POST['username'];
}

if ($_SERVER["REQUEST_METHOD"] == "POST") {
    echo "Hello " . $_POST['username'];
}

Object-Oriented PHP

Modern PHP development relies heavily on object-oriented programming (OOP). Classes, objects, inheritance, and interfaces help build scalable applications.

Example – Class and object:

class Car {
    public $brand;
    function __construct($brand) {
        $this->brand = $brand;
    }
}
$car = new Car("Tesla");
echo $car->brand;

class Car {
    public $brand;
    function __construct($brand) {
        $this->brand = $brand;
    }
}
$car = new Car("Tesla");
echo $car->brand;

PHP Security Best Practices

Security is crucial when working with PHP. Always validate input, use prepared statements for SQL queries, and sanitize output to prevent XSS and SQL injection.

Example – Prepared statement:

$stmt = $pdo->prepare("SELECT * FROM users WHERE email = ?");
$stmt->execute([$email]);

$stmt = $pdo->prepare("SELECT * FROM users WHERE email = ?");
$stmt->execute([$email]);

Conclusion

This PHP Cheatsheet covered syntax, variables, arrays, control structures, functions, file handling, database connectivity, OOP, and security. Keeping this quick guide handy helps developers write efficient, error-free, and modern PHP code.

As PHP continues to power millions of websites, mastering its essentials will always be an asset for web developers.

FAQs: PHP Cheatsheet